Rotten to the Core
by ForbiddenDreams13
Summary: Some people aren't meant to survive. What happens when a Sue decides to hatch a spirit beast


**Hello and welcome to a new oneshot!**

* * *

Koenma looked at the egg in his hand. Pale blue and now about the size of a pomegranate, it appeared rather innocuous. The shell pulsed, a thrumming vibration of energy as whatever resided in there turned over in its sleep. He sighed. Whether good or evil, he wouldn't know until it hatched. Not to say he didn't have a hunch as to how this endeavor would end. Placing the egg back on the cushion, he turned and exited the vault, slippers whispering over the cool stone. The heavy steel doors closed behind him and he found himself encased in the darkness of the caverns beneath the castle. Sconces affixed to the walls provided only the barest of light, the green spirit-fire merely poking at the shadows with thin, reedy fingers instead of rending them asunder. Koenma gazed at the doors. Finally, he shook his head and made for the castle. There was no sense in troubling himself over it.

Time would tell.

* * *

"Is it ready? Is my spirit beast ready to hatch yet?"

Koenma raised his eyes from the reports he'd been going over. The girl leaned over his desk, palms pressed down on various stacks of paperwork. The further she leaned, the more papers slid out of place. Lovely. When she left, he'd have to rearrange them. Again. This was the seventh time this month she'd been in his office to inquire about her spirit beast. Never mind the fact as to how she kept getting in. He looked around her at Botan. The ferry girl stood in the doorway, fiddling with the collar of her kimono. The poor woman looked worn out. The bright sparkle in her eyes had dimmed to a mere pinprick, her skin was pale, and even the blue of hair seemed faded. Koenma's heart went out to her. She'd gone from reaper to Yusuke's assistant to this girl's watchdog. Of course, Yusuke hated shoving her off onto Botan, but that was the only way the detective and the rest of the group could get any peace. It also kept Hiei from losing his temper and just outright killing the girl. _Then again,_ he thought, casting a glance at the mess she was making of his work, _I might just let Hiei slide on this one._

The girl narrowed her eyes. Almond shaped, and tipped with long lashes, they were an unnatural shade of green. Like a cross between the pale green of a cat's eyes and the insidious glow of a cloud of cave gas. It was a color that reminded him of all the unpleasant things associated with green: nuclear waste, poison, infections and the like. He despised her eyes. Of course, her pale skin and long, dark hair didn't help. She looked like she'd stepped out of a Victorian vampire tale. Minus the period clothing pf course.

Koenma sighed, "Well Lina-"

Lina huffed and drew herself up, "My name," she stated, tossing a shimmering lock of ebony over her shoulder, "is Lina Camille du Lac Rousell. It is a regal French name, and I would appreciate, at the very least, a 'Miss' before my first name."

Koenma fought the urge to roll his eyes. He knew what was coming next.

"As you well know," Lina continued, "my father was the Beast of Gevaudan, and my mother was a simple nun. I am half-wolf and deserve some respect!"

Botan put her head in her hands. Koenma wanted to throw her into the River Styx. Quirking an eyebrow at her, he replied "Your father was the great man-eating wolf that terrorized the Gevaudan region of 18th century France? You realize that would make you around two hundred years old?"

"Please, time is, well a little fluid shall we say, when you're not fully human."

This time Koenma did roll his eyes. "Of course."

"And you're wrong about my father by the way," she added.

Koenma rose from his desk. "Oh?" he asked, feigning interest while rummaging through a drawer in his desk. The end of his patience was drawing near. Best they end this dreadful business before it went any further.

"Yes," Lina responded with an arrogant nod, "the Beast of Gevaudan was actually a werewolf. A little known fact historians either get wrong or intentionally cover up." She sniffed, "but then again most of them are idiots anyway."

"Indeed." Koenma didn't care about her opinions and cared even less for her origin story. All that mattered was getting her out of his hair. He wanted her out of his detective's hair too, but until that egg hatched, they had to take what they could get. Nudging aside an ink bottle, he found what he was looking for. The small gold key gleamed in the light. He removed the key from the drawer. He really needed to get a box to keep it in. Just having it lay in a drawer anyone could open wasn't the smartest thing. Then again, that was assuming a potential thief could even get into his office in the first place. Kurama could, but he had no use for the key, or the room behind the door opened by said key. Lina watched him take the key from the drawer, lips pursed. He knew she wasn't counting on this visit being the one, but he also knew somewhere deep within she still hoped. Like the cocaine addict skulking through an alleyway looking for the dealer that provided them with their best hit, she couldn't help but come back and feed her desire. Of course, unlike that addict, Lina would get what she wanted. Maybe. There was still some chance that events would play out in Koenma's favor. The girl had been an unholy terror and everyone wanted to be rid of her. How the hell he'd been convinced to let her come back to life in the first place was beyond him.

Lina crossed her arms, "Well, are we going now?"

Koenma nodded, "Follow me."

For once, she did as she was told and didn't balk. Koenma exited the office with Botan and Lina in tow. The three of them walked down the length of the corridor, coming to a stop at the far wall. Affixed to the wall was a number pad. Koenma typed in the combination. The pad beeped and the wall slid back, revealing a staircase that led down deep below the castle. A chill breeze blew from the passage. Lina shivered. Botan rolled her eyes. Koenma could tell what the bluenette was thinking: _should have worn something more than a skin tight tank top and shorts._ The trio entered the cavern. The wall slid shut behind them, locking into place with a soft click. Darkness descended on them, thick and heavy, it pressed upon their vision. Koenma snapped his fingers and the sconces flared to life, emitting the same pale green spirit fire as before. The shadows receded, but not very far. Those nearest them thinned, while the spaces between the sconces remained dyed pitch black. Koenma made a note to look for a better light source. Maybe just good, old fashioned flame. He'd wanted electric lights, but they did things the old-fashioned way in Spirit World. Or so his father had said.

Koenma turned back to the two girls. Botan surveyed her surroundings while Lina kept her eyes locked on Koenma. He turned back and advanced down the stairs, Lina and Botan following. Silence dominated the tunnel. Water dripping from above, footsteps, even their breathing, the passage swallowed all sound. The corridor spiraled downward, going deeper and deeper into the bowels beneath the castle. The pale light within the sconces shimmered like a mirage. They followed the twisting staircase. Time trickled by, seconds turning into minutes that sank into the surrounding darkness until eventually, they reached the bottom. Before them stood a set of heavy steel doors. A strange mechanism welded into the metal. Gears, pistons, and chains cavorting across the door's surface in a snakelike pattern, all connecting to the lock in the center that stared back at them like an unblinking metal eye. Koenma walked up to the lock, inserted the key and twisted it. A loud thunk shook apart the thick silence, followed by clanking and whirring. The mechanism flared to life. Gears spun clockwise, pulling chains away from the door while pistons pumped the movements. After a moment or two of clanking and whirring, the mechanism stopped with a loud clang and the doors creaked open.

Littered throughout the vault were various items, all encased and each of them lit with an eerie blue glow that seemed to come from nowhere. Some were powerful weapons confiscated from the corpses of demons or humans who'd been undone by the arcane powers forged within them. Others were mundane items belonging to those who, while alive, had had some form of standing with the great Lord Yama. A few were unknown, both in origin and definition. It was theorized that these trinkets had slipped in from other dimensions. Koenma led Botan and Lina through the maze of guarded baubles to the center of the vault where Lina's egg resided. Unlike the rest of the items, it lay out in the open, no case necessary. After all, who could make any use of a spirit beast egg? The egg sat on a plush velvet cushion upon a pedestal. Koenma approached the egg. It had grown quite a bit. It was now the size of a small cantaloupe. He plucked it from the cushion. A heavy pulse thrummed from inside the shell. He could almost feel the presence of the creature within the egg. It was time.

He turned. Lina stood right behind him. Her green eyes glowed with excitement. She'd felt the pulse too. Botan stood a little ways off. No doubt she expected this to go south. Koenma didn't blame her.

"It's ready to hatch." Koenma announced.

Lina smiled and held out her hands, "That's wonderful!" she exclaimed, "Hand it to me!" She stepped forward, hands still outstretched, fingers flicking the air like tongues.

"Not so fast," Koenma moved the egg away from her, "do you remember the warning I gave you?"

Lina rolled her eyes, "Yes, yes. If I'm mean and nasty, it'll eat me. Big deal, we both know it's not going to go that way. Besides, I'll just go back to being a spirit anyway."

"No you won't. Should this beast be evil, it will devour you entirely. You won't be a ghost, your existence will simply cease. Body and soul go into this creature's gullet."

"Yeah, yeah, and that's real scary and all, but that's not going to happen to me."

The egg throbbed again. Koenma regarded it. "Are you sure?" he asked.

Lina stamped her foot, "Yes, I'm sure! Everyone tells me how great I am, and Yusuke and his friends all love me! Besides, I have incredible power, so why would I turn out evil? Power like mine is only used for good!"

 _History says otherwise_ Koenma thought. He shifted his gaze from the egg to Lina. Fifty/fifty. Those were her odds. One or zero. Black or white. Soup or salad. They had reached the fork in the road. Now, all that was left was to find out which path Lina would be pushed down. With nothing else to say, Koenma handed Lina the egg. She snatched the egg from the prince and clasped it in her hands. The egg pulsed once more. Then again. And again. With each pulse, the egg lit up, blue light flaring across Lina's lily white skin. The pulses quickened with each passing second until the egg emitted a constant glow. A deep humming issued from the egg, constant vibration drawn out into one long drone. A crack appeared, a thin black line. Lina gasped. The crack crawled across the shell's expanse in a zigzag pattern. Each little right angle branched off into small web-like tendrils, grasping for more shell to destroy. The cracks deepened, stretching, connecting. The entire egg became a network of criss-crossing breaks. For s single heartbeat, it froze. No vibration, no more cracking. Then, it burst apart. A blinding glow enveloped all three of them. Koenma shielded his eyes from the sudden influx of light. When it vanished, the prince of Spirit World lowered his hand and looked around. Lina stood in front of him, pieces of the shell lay scattered about her. Botan had moved a bit closer and now stood off to the left of Koenma. Just them. No beast. Koenma frowned. Something wasn't right.

Lina looked all around, "Where is it? Where did it go?" She glared at Koenma, "You did something to the egg, didn't you?!"

"What? No, I-"

A horrid scream from deep within the vault cut him off. It sounded like someone trying to shout with a throat full of broken glass. Botan shivered and edged closer to Koenma. The scream sounded again, closer this time. Fifty/fifty. The coin had landed face-down. Shuffling, irregular footsteps drew closer. Lina trembled.

"Wh-what is that?"

"I think that's your spirit beast."

Before Lina could object, the beast sauntered into view. Koenma felt the blood drain from his face when he saw it. Sallow, pock-marked skin riddled with gashes covered the thing. Koenma squinted at the beast. Wait, those weren't gashes, they were mouths! As if in response to his realization, one of the mouth opened up. Foul, thick yellow liquid oozed from the orifice. An idiot tongue lolled out of the lipless maw, licking across small, rotten teeth. The creature shambled forth on four appendages that resembled either legs or arms. Koenma couldn't be sure. The flesh beneath the skin moved and undulated, not twitching, but rather swimming beneath the leather canvas of its hide. Making the creature both bloat out and slim down. Its form, as a result, was difficult to pin down. A strange sack dangled at the front, bobbing and swaying with each movement it made. It flapped up for a brief moment and Koenma saw several bulges littering the front. They blinked open and a multitude of pink, watery eyes stared at him. Koenma deduced that that sack was the thing's head.

Lina opened her mouth to scream, but all that came out was a choked whimper. Botan now stood right next to Koenma, gripping the prince's arm in terror.

"N-No…" Lina murmured, "This can't be right."

"It is." Koenma said, "Remember, I told you the beast reflects your true self. Not what you or other people you are, but how you really are."

Lina whipped around. "Liar!" She shouted, jabbing a finger at Koenma. "This is your fault! Fix it! _Now!_ "

Koenma shook his head, "You agreed to the terms. Whether or not you stopped to consider them is not my problem. This creature was born from you. Your thoughts, actions, desires, everything. _You_ created this monstrosity, not me."

Lina clenched her hands into fists. Dark rage rolled off of her in waves. Righteous indignation blazed in her eyes. She pulled back a fist. Koenma didn't move. "How dare you!"

She swung. Her fist never connected. The creature raised itself up on its hind appendages. There was a sickening squishing noise as its forearms (legs?) stretched and shot out, wrapping around Lina's arm. The tendrils flattened, widening into thick bands, covering her entire upper arm. Lina cried out. Crimson rivulets of blood seeped out from underneath the fleshy trappings. With dreaded certainty, Koenma knew the mouths on the creature's arms had begun to feast. The abomination used its hold on Lina to stagger closer. Once in range, the mouths on the torso yawned open, tongues shooting out and jabbing into Lina's skin like pink, fleshy needles. Blood spurted from the wounds, splattering the beast's skin. The mouths on the hind legs grinned. The tongues wiggled, digging deeper into Lina. Lina screamed. Botan buried her face in Koenma's shoulder.

With her free hand, Lina reached out for Koenma. Koenma did not move. This monster was a result of her innermost self. She had made her bed, littered with sins and sewn up in selfishness. Now she had to lay in it. The creature pulled Lina back against its bulk. The swimming flesh deformed the being and it sank around the Lina's body, enveloping her within itself. The rest of its mouths crunched on exposed parts of Lina's flesh. The eyes on its sack head wept a sticky pus that sizzled upon contact with the girl's skin. As Koenma watched, he saw her skin bubble and burn. Lina wailed in agony. Koenma felt his gorge rise, but fought it down. It wasn't the first time something like this happened, and it would not be the last. The monster's flesh continued to fold around its prey. Lina's screams dwindled to muffled shrieks. Somehow, those were more disturbing than the clear, shrill ringing of her screams. Blood puddled on the floor around the thing's feet. Muted crunching and suckling met Koenma's ears followed by more muffled cries. The creature's bulk began to sink down to the floor as it consumed more and more of Lina's flesh. Eventually, it collapsed onto the ground, tongues waggling out from underneath its body, sucking up the spilled blood with greedy glee. When the last shred of Lina's existence had been devoured, the beast stood up. It regarded Koenma for a moment, then faded out, like the remains of a terrible nightmare upon daybreak. In some ways, Koenma supposed that was what that thing was.

He looked down at Botan. The poor girl was still cowering into his robes. Patting her head, Koenma murmured, "It's over now Botan."

Slowly, Botan edged away from her safe haven. Her gaze darted around the vault looking for both the girl and the horror she spawned. When she found neither, she looked back at her superior, confusion marring her face, "Where did it go?"

Koenma shrugged, "I don't know. That always happens whenever a spirit beast devours its creator. I think it's some kind of paradox thing. The spirit beast is, in essence that person's other half. If they get hurt, so does it and vice-versa. It would stand to reason, that if the person were to be erased from this world, so would the spirit beast. Or so my theory goes. Either way, it beats having stray minsters running around devouring people."

"I suppose." Botan said, staring at the spot where Lina had been devoured. She turned to Koenma, "I suppose Yusuke and the others will want to hear the news."

"Oh indeed," Koenma agreed, nodding his head. And with that, the two of them exited the vault and after locking the door, made their way back into the castle. Botan left to Human World to inform Yusuke and crew of Lina's fate. Koenma believed there would be quite a few relieved sighs. He felt a little guilty for feeling such glee, but then again the world wasn't full of good people. There were quite a bad apples out there. With apples like Yusuke, only the skin was browned and bruised, but with so many others, their rot went right down to the core. So in the end, he wouldn't worry about it.

Some people just aren't meant to survive.

* * *

 **I've always wondered how things would go down if a spirit beast turned out a little less than friendly. While Lina is a Mary-Sue, I'm not sure I would call this a parody. Sue Wish-Fulfilment perhaps? Either way, thanks for reading! Drop me a review if you like!**


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